In a typical semiconductor process, dice are cut from wafers by a dicing process, then each die is attached to a package substrate or a chip carrier of a leadframe, the inputs/outputs of the die are electrically connected to leads of the leadframe by a bonding process, and finally, plastic, ceramic or metal is used to encapsulate the die except that the outer leads of the leadframe are left exposed outside the package for connecting to other electronic components. This process is called electronic package method. With the protection of the electronic package, the IC components in the die may avoid damages from external environment or forces.
For an electronic package, there are three popular bonding processes, wire bonding, tape automatic bonding (TAB) and flip-chip bonding, among which the wire bonding is the most often used. The wire bonding process uses a bonder to bond one end of a wire to a bonding pad on a die and the other end to a lead of a leadframe. The commonly used wires include aluminum wires, gold wires, silver wires and so on. The thickness of a single wire or the number of wires will be proportional to the current to be carried. The greater the current to be carried, the larger the thickness of a single wire or the number of wires is. For instance, for power input and output of a power management chip, sometimes more than five bonding wires are bonded to a bonding pad of the chip because great current will flow therethrough. Such high current applications result in high cost and low yield packages. In some circumstances, for example, if non-uniform contact resistance is present between several wires bonded on a same bonding pad, or some of the bonding wires are broken, there will be a single one among the bonding wires carrying the high current and thus being broken.